In slaughtering a live animal in an abattoir for production of meat, hide, and other by-products, the animal is usually restrained and then stunned to induce immediate unconsciousness and insensibility. The slaughter can then be performed without avoidable fear, anxiety, pain, suffering and distress. The stunning can also help avoid difficulties and dangers for persons involved in the processing and handling operations. The “stunning” is commonly carried out either by a mechanical process, such as applying concussion by means of a projectile captive bolt (penetrating or non-penetrating mushroom headed knocker) impacted against the skull of the animal, or by electrical current applied to the animal and passed through the brain, or by inhalation of gases such as carbon dioxide, nitrogen or argon.
The terms “stun” or “stunning” are frequently used to refer to irreversible processes, i.e., the “stunning” process causes irreversible damage to the animal, particularly the brain. This may not be a difficult or contentious issue with regard to animal welfare concerns because the slaughter, such as by sticking and exsanguination, immediately follows the stunning and is, therefore, performed on an irreversibly unconscious and insensible animal.
However, with religious slaughter or ritual slaughter, irreversible stunning is not acceptable. The animal must not be injured or harmed prior to exsanguination. For example, with the Muslim slaughter method or “Halal slaughter,” the animal is required to be alive at the time of slaughter. This requirement does not necessarily mean that the animal is not permitted to be first stunned prior to slaughter, as long as there is no injury, e.g., significant damage to the skull, but irreversible stunning may well be unacceptable to comply with the dictated ritual requirements. Likewise, with the Jewish or Judaic slaughter method or “Shechita,” post-cut stunning of the animal may be permissible, but not irreversible pre-cut stunning that may be deemed unacceptable so that the resulting carcass would not be Kosher.
There have been some references in the published patent literature to use of microwave radiation stunning of animals for slaughter.
U.S. Pat. No. 3,973,290 refers to stunning an animal for slaughter by applying microwave energy to penetrate the animal's skull and heat the brain. A microwave beam is proposed to be directed at the animal without restraining it, the energy being applied from the side of the skull. Such methods of application would create considerable surrounding tissue damage by largely indiscriminate heating and, therefore, would be an irreversible process, causing harm to the animal, and is likely to be inhumane.
U.S. Pat. No. 4,616,160 describes a microwave heating apparatus for irradiating the entire head of test animals, particularly rodents. The configuration of the apparatus, including the manner of coupling the microwave energy to the animal, will heat the entire head of the animal. The specification does not explain whether the purpose is to stun the animal but, if so, many organs and tissues of the head are likely to be damaged and the apparatus would, therefore, be unacceptable from the point of view of animal welfare.
DE 4116670 describes and illustrates an apparatus for irradiating a pig with multiple microwave applicators arranged around the head and in a row along the length of the spine, all being spaced from the animal. Use of such an apparatus design will irreversibly damage tissues by cooking affected tissues, which is likely to be inhumane.
JP 3039615 describes apparatus for slaughtering animals using microwaves to heat the brain causing cerebral death.
WO2011/137497 describes an animal stunning apparatus and method for inducing rapid unconsciousness and insensibility. The apparatus includes a stunning station in which a live subject animal is located in a confined position and an applicator contacts an application point on the live subject animal's head immediately overlying a frontal portion of the animal's brain and couples microwave radiation to the head. A microwave generator generates microwave energy of a suitable power level and frequency, and a waveguide directs the microwave radiation to the applicator. A switch discontinues the application of microwave radiation effecting heating of the frontal portion of the brain after a period of time sufficient to have raised the temperature of the frontal portion of the brain of the subject animal to thereby induce the unconsciousness and insensibility. The period is sufficient only to rapidly induce insensibility, and is insufficient for the insensibility induced to be irreversible, and insufficient to cause significant heating of deeper brain tissues including the brain stem. This system is owned by the present applicant and testing and development of this system revealed significant and unexpected difficulties in achieving consistent results for the animal stunning, making the system unsatisfactory commercially and/or for animal welfare.
The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art in Australia or elsewhere. None are known to have been ever commercially used.